The versatility of polyamides has led to their use in applications ranging from structural components to hot melt adhesives. Part of this versatility arises from the fact that the composition of the backbone of the polymer can be varied to yield specific properties by adjusting the components from which the polymer is synthesized. Currently, several nylon manufacturers incorporate polyoxyalkyleneamines into their products to modify the final properties. The polyether backbone of these components improves the comfort feel, wickability and dyeability of textile grades. In general, polyetheramines improve impact and antistatic properties of nylon.
A. Hardy, "Polyester, Polyamide and Polyurethane Melt Adhesives," Crit. Prep. Appl. Chem., Vol. 16, 1987, pp. 31-58 gives an overview of a number of adhesive types. The descriptions of polyamides begins on page 45 and polyether-containing polyamides are mentioned on page 49. It is noted that polyamide resins can also be made water soluble, but it is not described how this is done. This survey gives a brief description of technology described in U.S. Pat. Nos. 4,128,525; 4,162,931 and 4,182,845. These patents involve thermoplastic adhesive components, prepared from inexpensive and readily available synthetic materials, having melting points between about 20.degree. C. to about 180.degree. C. and broad ranges of hardness, flexibility and compatibility. The thermoplastic compounds useful in adhesive formulations are comprised of a resinous polyamide reaction product of a polyoxypropylene polyamine having an average molecular weight of from about 190 to about 3,000 and being selected from diamines, triamines or mixtures thereof, piperazine and an aliphatic or aromatic dicarboxylic acid, ester or anhydride having from about 4 to about 20 carbon atoms per molecule. The resinous polyamide reaction product is prepared by mixing and reacting the polyoxypropylene polyamine, piperazine and dicarboxylic acid materials in a total amine:acid molar ratio within the range of from about 0.25:1.0 to about 4.0:1.0 at a temperature of from about 175.degree. to about 270.degree. C. The thermoplastic polyamides can be formulated with compatible plasticizing agents to prepare a useful adhesive to which can also be added other components, such as a minor amount of a polyepoxide resin having an epoxide equivalent weight of about 150 to about 600, fillers and the like to produce thermoplastic adhesive formulations having desired hardness, flexibility and compatibility that are capable of bonding together a variety of substrates.
Block copolyetheramides were prepared by incorporating polyether into polyamide through melt polycondensation of polyetherdiamine, piperazine, dimer acid and .epsilon.-caprolactam, according to A. T. Hu, et al., "Preparation of Block Copolyetheramides and their Properties as Hot Melt Adhesives," Journal of Applied Polymer Science, Vol. 37, pp. 1863-1876 (1989). Bulk properties of block copolyetheramide, such as tensile strength, tensile modulus, elongation at break, hardness and impact strength, were evaluated with respect to composition. Investigation on the lap shear strength and T-peel strength of block copolyetheramide hot melt adhesive showed that the lap shear strength was more composition-dependent.
G. Russel in "Water Soluble Hot Melts," Materiaux et Techniques, March-April 1990, pp. 57-58 mentions the need for adhesives which are affected by water including total solubility thereof, and goes on to describe polyvinylpyrrolidine/vinyl acetate copolymers, some of which are water soluble.
Patents of particular interest include U.S. Pat. No. 4,229,567 which discusses that copolyamides derived from a mixture of short-chain and long-chain saturated aliphatic dicarboxylic acids, piperazine and a polyoxyalkylene diamine are excellent hot melt adhesives useful with a variety of substrates. These thermoplastic copolyamide resins are particularly useful adhesives for vinyl materials and are resistant to creep.
A hot-melt adhesive comprising copolyamides obtained from (a) .epsilon.-caprolactam, (b) diamine salts of adipic acid, sebacic acid and/or azelaic acid and (c) alkylenedicarboxylic acid salts of polyether-diamines gives e.g. textile laminates which are particularly resistant to washing and dry cleaning, according to U.S. Pat. No. 4,024,116.
Other relevant patent literature includes U.S. Pat. No. 3,945,983 which describes a process for the production of an anchoring agent of copolyamide resin by condensing certain amounts of polyalkylene polyamines, dicarboxylic acids and at least one member of the group of diamine, .epsilon.-caprolactam and amino caproic acid, and then reacting the secondary amino groups of the copolyamide partially with epichlorohydrin for crosslinking.
U.S. Pat. No. 3,989,678 discusses a hot melt adhesive which comprises a copolyamide consisting essentially of (1) .epsilon.-caprolactam, (2)(a) hexamethylenediamine and (b) at least one straight chain, saturated aliphatic dicarboxylic acid having 6 to 20 carbon atoms in a substantially equimolar ratio and (3)(a) at least one of 2,2,4-trimethylhexamethylenediamine and 2,4,4-trimethylhexamethylenediamine and (b) at least one straight chain, saturated aliphatic dicarboxylic acid having 6 to 20 carbon atoms in a substantially equimolar ratio; all being within certain proportions.
The flow characteristics and rheological properties of high molecular weight thermoplastic polyamides are significantly improved by blending therewith a small amount of a polyamide derived from high molecular weight dibasic acids as disclosed by U.S. Pat. No. 4,062,819. In addition to improving the processability of the thermoplastic resin, the blends and manufactured articles produced therefrom have other desirable properties.
U.S. Pat. No. 4,150,002 mentions polyamides and polyesteramides having melt viscosities from 25 to 600 Pa.s at 220.degree. C. and useful as melt adhesives for textiles. The materials are condensation products formed between (a) a dimerized fatty acid component containing at least 70 percent of dimeric acid; (b) a C.sub.6 -C.sub.13 aliphatic straight-chain codicarboxylic acid; (c) a C.sub.6 -C.sub.12 aliphatic straight-chain diprimary diamine; and (d) caprolactam and/or .epsilon.-aminocaproic acid. The polyesteramides additionally contain a further component (e) which is caprolactone and/or .epsilon.-hydroxycaproic acid.
A polyamide adhesive for bonding fabrics, particularly fusible interliners for fabrics, which are cleanable by laundering and/or dry cleaning is disclosed in U.S. Pat. No. 4,217,256. The polyamide adhesive is a terpolyamide of caprolactam and hexamethylene diamine with a mixture of polymeric fat acids and an aliphatic co-dicarboxylic acid having 20-22 carbon atoms.
Flexible, homogeneous and transparent copolyamides comprise the polycondensation products of adipic acid, fatty acid dimer and hexamethylenediamine according to U.S. Pat. No. 4,452,974, where the molar ratio of weight of adipic acid to weight of total acid in each ranges from about 0.5 to 0.99. The copolyamides are prepared either by polycondensing a homogenized prepolymer thereof, or by directly copolycondensing a homogeneous, inert solvent solution of monomers. The homogeneous and transparent copolyamides exhibit improved flexibility and high tenacity coupled with good resistance to hydrolysis and good heat resistance, with the copolyamides being useful for providing shaped articles such as moldings, films or filaments of marked uniformity via injection molding, extrusion or spinning.
U.S. Pat. No. 5,086,162 to Texaco Chemical Company describes novel polyether amides produced by reacting at least one polyalkylene glycol diamine with at least two dicarboxylic acids or esters thereof. The polyethylene glycol diamine has the formula NH.sub.2 --(CH.sub.2 CH.sub.2 O).sub.x CH.sub.2 CH.sub.2 NH.sub.2 where x ranges from 2 to 6, and at least one of the dicarboxylic acids is an aromatic dicarboxylic acid. Suitable dicarboxylic acids include adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, t-butyl isophthalic acid and mixtures thereof. Suitable diamines include triethylene glycol diamine (JEFFAMINE.RTM. EDR-148 amine) and tetraethylene glycol diamine (JEFFAMINE.RTM. EDR-192 amine), among others. The resulting polyether amides are useful to make polymers, including fibers, with unusually good water absorbancy properties. The described methods successfully incorporated triethylene glycol diamine and aromatic dibasic acids, where this cannot be accomplished directly.
Polyether amides may be produced by reacting aromatic dicarboxylic acids with tetraethylene glycol diamine according to U.S. Pat. No. 5,118,785, also to Texaco Chemical Co. This discovery was noted as surprising since aromatic dicarboxylic acids, such as terephthalic acid cannot readily be reacted with triethylene glycol diamine. Suitable dicarboxylic acids include terephthalic acid, isophthalic acid, t-butyl isophthalic acid and mixtures thereof. The resulting polyether amides are useful to make polymers, including fibers, with unusually good water absorbancy properties.
Dimer acids, obtained by the dimerization of C.sub.18 acids such as oleic acid and linoleic acid are especially useful for the preparation of water insoluble hot melt adhesives. These dimer acids have as their main components C.sub.36 dicarboxylic acids and C.sub.54 tricarboxylic acids. Polyamides made from these acids for the hot melt industry are used in laminating metals, plastics and shoe soles to uppers. The resin is applied in liquid melted form and adhesion occurs almost instantly; cooling results in a strong adhesive bond.
It would be desirable to make water soluble polyamides from dimer acid so that one could take advantage of the desirable properties this dibasic acid brings to such products.